1. Technical Field
This application relates to techniques data storage systems such as data storage arrays and more particularly to techniques used in connection with upgrading physical drives of a data storage system.
2. Description of Related Art
Computer systems may include different resources used by one or more host processors. Resources and host processors in a computer system may be interconnected by one or more communication connections. These resources may include, for example, data storage devices such as those included in the data storage systems manufactured by EMC Corporation. These data storage systems may be coupled to one or more servers or host processors and provide storage services to each host processor. Multiple data storage systems from one or more different vendors may be connected and may provide common data storage for one or more host processors in a computer system.
A host processor may perform a variety of data processing tasks and operations using the data storage system. For example, a host processor may perform basic system I/O operations in connection with data requests, such as data read and write operations.
Host processor systems may store and retrieve data using a storage device containing a plurality of host interface units, disk drives, and disk interface units. The host systems access the storage device through a plurality of channels provided therewith. Host systems provide data and access control information through the channels to the storage device and the storage device provides data to the host systems also through the channels. The host systems do not address the disk drives of the storage device directly, but rather, access what appears to the host systems as a plurality of logical disk units. The logical disk units may or may not correspond to the actual disk drives. Allowing multiple host systems to access the single storage device unit allows the host systems to share data in the device. In order to facilitate sharing of the data on the device, additional software on the data storage systems may also be used.
In connection with a data storage system, it may be necessary to upgrade the firmware on one or more of the physical drives. Some systems may perform firmware updates to physical drives whereby the physical drives and, more generally, the entire data storage system including such physical drives, may be taken offline. In this manner, the physical drives are unavailable to service host I/Os during the firmware updating of the physical drives where applications on the host issuing such I/O operations to the physical devices are stopped. Additionally, the data storage system may be rebooted multiple times as part of the firmware update process. Some systems may perform online firmware updates whereby host-data storage system connectivity may not be lost. However, such online updates may only allow firmware upgrade of a single physical drive per each RAID group and may be time consuming due to this restriction. Additionally, some online firmware update techniques may not allow for updating any physical devices not configured to have a mirror.